Children rest at a refugee camp in Bayeun, outside of Langsa, Indonesia, May 20. They were among the 25,000-plus Rohingya Muslim migrants who have fled reported persecution in Burma and Bangladesh this year by crossing the Indian Ocean in search of refugee status in Indonesia and Malaysia.James Nachtwey for TIME

Children rest at a refugee camp in Bayeun, outside of Langsa, Indonesia, May 20. They were among the 25,000-plus Rohingy

The Plight of the Rohingya by James Nachtwey

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For decades, TIME contract photographer James Nachtwey has used his camera to give form to the invisible. Yet in a world filled with persecuted people hidden in isolated corners of the globe, the Rohingya stand out. A Muslim minority from western Burma, the 1.3 million-strong Rohingya have been denied the most basic of human rights: citizenship. Their sense of self has been lost.

Since sectarian tensions erupted in 2012, roughly 140,000 Rohingya have been herded into camps by the Burmese government, which has allowed a virulent Buddhist nationalist movement to germinate. Last year, Nachtwey spent time in these Rohingya ghettos, where conditions were among the worst he had witnessed — and this from a photographer who has worked in refugee camps in Africa and the Middle East.

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With limitations on their lives increasing with each month — in May, Burmese President Thein Sein signed a population-control law that could be used to restrict the number of children Rohingya bear — Rohingya have been boarding rickety boats in hopes of eventually landing in Malaysia, a Muslim-majority nation where they take menial jobs. Over the last year or so, around 90,000 Rohingya and Bangladeshi migrants, who also hope for better economic prospects, have embarked on perilous journeys that take them across the Bay of Bengal and Andaman Sea to the jungles of Thailand and Malaysia. Often, the price agreed upon for the feat of human-smuggling rises once the migrants stumble into the jungle encampments. Unless family members pay up, the Rohingya and Bangladeshis face possible starvation, disease and even execution by the traffickers.

With Thailand and Malaysia finally cracking down on the trade, the human-smuggling trawlers — slave ships, really — have turned into floating prisons, as the normal trade routes are disrupted and captains abandon their boats. Thousands may still be stuck at sea. Meanwhile, on land, authorities have found more than 150 graves of suspected migrants, near abandoned jungle camps. Police and government officials have been detained for their part in the trafficking trade.

The Rohingya, Burma's Forgotten Muslims by James Nachtwey

More than 140,000 minority Rohingya Muslims have been forced to live in camps, where disease and despair have taken root. Abdul Kadir, 65, who has a severe stomach ailment and malnutrition, is cared for by his wife in one of the camps.James Nachtwey for TIME

More than 140,000 minority Rohingya Muslims have been forced to live in camps, where disease and despair have taken root

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James Nachtwey for TIME

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In May, Nachtwey traveled to three countries — Thailand, Indonesia and Malaysia — to document the plight of Asia’s newest boat people. In Malaysia, he trekked through jungle to observe bodies being pulled out of the earth, near encampments with bamboo cages used to confine migrants. At a temporary refugee camp in Indonesia’s Aceh province, he captured an equally affecting scene: Rohingya who had spent more than three months at sea, starving and forced to drink their own urine, patiently lined up just a day after they had come ashore. One by one, they stood in front of an Indonesian photographer, who documented their names, ages and addresses — Burma was listed as their country of origin — on a whiteboard. Long unable to claim any real identity, the Rohingya were finally being given a chance at self-expression. As always, Nachtwey was there to bear witness.

Hannah Beech is TIME’s East Asia Bureau Chief and traveled with Nachtwey to report on the plight of the Rohingya.

James Nachtwey is a TIME contract photographer, documenting wars, conflicts and critical social issues.